1. Field of the Invention
The present invention relates to an image recording apparatus and, more particularly, to an image recording apparatus in which a recording media which cannot be overwritten is applied.
2. Related Art Statement
A conventional image recording apparatus in which a magnetic recording media such as a floppy disk is applied as a recording media for image information is known. In such an image recording apparatus, image information is recorded as an analog signal in each track area on concentric circles formed on the recording media. When an erasing operation is to be performed, an erasing operation is magnetically performed to a corresponding track area to erase the image information in the track area.
In recent years, as an image recording apparatus called a digital electronic still camera, an image recording apparatus in which digital data based on image information is recorded on a semiconductor memory such as an S-RAM or the like serving as a recording media has been popularized. In an image recording apparatus such as a digital electronic still camera, image information originally consists of digital data. For this reason, the image recording apparatus has been not only used as a recording apparatus for image information, but also has occupied a very important and superior position as a tool for picking up an image in an image system environment using personal computers or the like.
Therefore, in such an image recording apparatus, as an image data management format in the recording media, a format following a DOST FAT file system which is extremely popularly used in the above information system environment is advantageously used.
The logical structure of an image data recording media based on a DOS system, and the outline of the management of image data recording media will be described below. FIG. 19 shows the logical structure of the recording media. The media serving as a recording media is roughly constituted by the four following areas:                (1) an area 31 in which a parameter representing a logical structure is described.        (2) a first management area 32a in which a map representing the position of a file in a data area is recorded (number of sectors in this area is (sector/FAT)×2)).        (3) a second management area 32b, having a fixed size, in which the name and file size of a registered file (number of sectors in this area is (total number of root directory entries)+(number of bytes/sector+32)).        (4) an area 33 which is used as a recording area of the main body of data of a registered file and/or a sub management area where sub-directory information is recorded (number of sectors in this area is (total number of sectors in the media—(number of sectors of a root directory+number of sectors per FAT×number of FATs+number of reserved sectors)).        
In a DOS FAT (FILE ALLOCATION TABLE) file system, of the above areas, the area 31 is called a boot sector; the first management area 32a, an FAT; the second management area 32b, a root directory (data management area); and the area 33, a data recording area.
In the root directory of the area 32b, since the number of entries which is predetermined for each media is determined, when only a data file is registered, only files corresponding to the number of entries are registered. For this reason, not only a file but also a new directory (sub-directory) can be registered in the directory. In any case, the main body of a file or a directory to be registered is recorded in the data recording area 33.
A recording position of the data area, registration to a media, and deletion are managed by the directory and the FAT 32a. When a file or directory is registered in the root directory 32b, a file name, a directory name, auxiliary information such as a file size and a date, and the entry number of the FAT 32a are recorded in the entry. The data recording area 33 is divided into logical recording units called, e.g., clusters 34.
Each entry of the FAT 32a is one-to-one-related to each cluster of the data recording area. In the entry of the FAT 32a, the number of an entry to be traced next and a code representing the final entry (no entry to be traced next) or an unused entry are recorded. Therefore, a specific cluster, in the data recording area 33, in which data or a directory is recorded can be recognized in the following manner. That is, the entry of the first FAT described in a directory entry is accessed, and entry numbers written in the entry are sequentially traced.
The above is a mechanism of registering and reproducing a file or a directory. In a sub-directory, the entry area of a directory is only placed in the data recording area 33. The management of files and directories registered in the sub-directory is the same as that in a root directory.
An erasing operation performed by an erasing mode in a conventional image recording apparatus is a so-called pseudo erasing operation, and means a process in which the start of a file name recorded in an entry of the area 32b in FIG. 19 is set to 0, the area of the FAT 32a in which a cluster number on which the data of the file is placed is described is set to FFh (h indicates hexadecimal notation). Therefore, in a conventional image recording apparatus, the data in a file which is erased is still left in the data recording area 33.
In an image recording apparatus such as a conventional digital electronic still camera described above, when image data is to be erased, a predetermined process such as an erasing process is performed to an image data management area such as a known directory area in a DOS FAT file system, so that image data in the image data recording and is pseudo-erased. When the recording media is constituted by an S-RAM, even if image data is temporarily left in the image data recording area, over-writing can be performed. For this reason, a recording operation for subsequent image data can be performed without any inconvenience.
In recent years, a recording media using a flash memory which is a semiconductor memory and cannot be overwritten such that recording/erasing can be repeated without a backup power supply as used in an S-RAM begins to be used as an image recording apparatus of this type.
However, when the recording medium which is constituted by a flash memory or the like and cannot be overwritten is applied to the image recording apparatus for the conventional digital electronic still camera described above, the following problem is also posed.
More specifically, even if a predetermined process is performed to an image data management area in the same manner as described above as in a case wherein a media using an S-RAM is applied to erase image data in a recording media in the image recording apparatus of this type, although a pseudo erasing operation for the image data can be performed, subsequent image data cannot be recorded in the image data recording area because the media cannot be overwritten. Therefore, the necessity of a substantially erasing operation for image data which is performed independently of a pseudo-erasing operation further rises.
As a result, assume that a recording mode is set, and that a rare recording chance, i.e., a chance of pressing a shutter release comes. In this case, when image data is not substantially erased, a time-lag is required to perform the substantially erasing operation. For this reason, the image is missed, and desired image information cannot be recorded on the recording medium.